An exponential increase of data and resultant difficulty in processing data become more serious in an exascale class cloud storage environment. In particular, storage spaces which are not well utilized make it more difficult to manage storages.
Furthermore, this problem may cause waste of storage resources and also incur much cost in operating the storage resources. Since problems of other aspects may arise, there is a need for an improved method.
Methods utilizing archiving technology have emerged, but they are not regarded as effective methods due to unsatisfactory service quality.